大二上学期文件-细胞生物学chapter10cytoskeleton

110.cellcytoskeletonandcellmotility2Cytoskeleton(细胞骨架):thenetworkcomposedoffibroid(纤维状)proteins

ineukaryoticcells,includesthemicrotubule(微管),

microfilament(微丝)andintemediatefilament

(中间纤维).General

cytoskeleton:cytoplasmicskeleton,nuclearmatrixandcellmembraneskeleton.3aroundthenucleusinastar-likecytoplasmicarraytheinnerfaceoftheplasmamembranethroughoutthecytoplasm柔软束状或网状柔软,绳状长直坚硬Cytoplasmicskeleton4OUTLINE◆MICROTUBULES◆MICROFILAMENTS◆

INTERMEDIATEFILAMENTS51.Microtubules(MTs)1)MorphologicStructure◆long,hollow,cylindricalstructures◆outerdiameterof25nm,◆innerdiameterof14nm◆wallthicknessofapproximately5nm◆lengthbeingvariable62)Chemical

component◆Themicrotubulesconsistoftwotypesoftubulin(微管蛋白)molecules：α-tubulin

andβ-tubulin；●eachαorβmonomerhasabindingsiteforamoleculeofGTP.TheGTPontheα-tubulinisneverbehydrolyzed.Thenucleotideontheβ-tubulinmaybeineithertheGTP

ortheGDPform,anditisexchangeable.●otherbindingsitesfordivalentcationandspecificdrugs.73)Assemblyofmicrotubulesαβheterodimersof8nminlength13条原纤维纵向排列组成微管的壁微管的形成GTP帽(GTPCap)(片状结构)(原纤维)8(1)PeculiaritiesofMTassembly◆

Structuralpolarity--eachprotofilament:tubulindimerswithα-andβ-tubulinalternating--Tubulinsubunitsassemblehead-tailtogeneratefilaments--(+)endassemblesmorerapidly“+”端(plusend)和“-”端(minusend)9◆Dynamic

peculiarities

----Dynamicinstability(动态不稳定性):Thisrapidinterconversionbetweenagrowingandshrinkingofmicrotubule,atsomefreesubunitconcentration.有丝分裂前期和末期发生10----Treadmilling(踏车现象--轮回现象):Ahomeostasis

phenomenonthattheplusendgrowswhilethe

minusendshrinksduringelongationofmicrotubules.11Dynamicinstabilityandtreadmilling:与反应体系中游离α、β二聚体的浓度变化有关

◆Criticalconcentrationoftubulindimers(Cc,微管蛋白临界浓度):theconcentrationatdynamicequilibriumbetweentubulindimersandMTtheconcentrationofdimers＞Cc

theconcentrationofdimers＜Cc◆Dynamicinstabilityandtreadmillingaidrapidcytoskeletalrearrangement12invivomicrotubuleassemblyMTOC(microtubuleorganizingcenters--微管组织中心):

generatinglocus(核心)ofreassemblyafterMTdepolymerizationininphysiologicalstatusorexperimentaltreatment.

(-)endpointstoMTOC，Basalbody(基体)andcentrosome(中心体)formtheorganizingcentersforthemicrotubules.中心体由中心粒和中心粒旁基质组成在分裂间期，在核附近，在分裂期，在纺锤体两极。13（树突）中心粒胞质微管轴丝微管（轴突）中心粒基体只含一个中心粒植物细胞无中心体，其微管组织中心是核外被表面的成膜体（phragmoplast）14γ-tubulinring(γ-微管蛋白环）(+)end(-)endγ-tubulin通过与β

–tubulin蛋白相互作用帮助微管成核15(2)Factorsthataffectmicrotubuleassembly

Thecriticalconcentrationoftubulindimers,

GTP,

pH(最适6.9),temperature（37℃）,pressure,Ca2+,andaccessoryproteins,chemical

drugs16Theconcentrationoftubulinheterodimer,GTPcapmicrotubuleassemblyandGTPcapat(+)poleend17◆MAP(MicrotubuleAssociatedProtein,微管结合蛋白）

MAPshavetheMTbindingdomains,oneendbindingtoMT,otherendbindingto

adjacent

MT,cellmembraneorothercytoplasmicskeleton.

stabilizeMT18MAPs的功能◆使微管相互交联形成束状结构;◆促进微管的聚合;◆提高微管的稳定性,防止微管的解聚。◆作为分子发动机(Molecularmotor:convertchemicalenergyintomechanicalenergy)转运细胞物质的轨道;19Typesofmolecularmotors(分子发动机)◆Motorproteins(发动机蛋白)canbegroupedintothreebroadfamilies:●驱动蛋白(kinesins)家族

Tomovealongmicrotubules(从(-)端向(+)端的运输)●动力蛋白(dyneins)家族

Tomovealongmicrotubules(从(+)端向(-)端运输)●肌球蛋白(myosins)家族

Tomovealongmicrofilaments.20动力蛋白驱动蛋白tomovecellularcargoattachedtothemotor21◆Drugsspecifictomicrotubuleassembly--Colchicine(秋水仙素)andvinblastine(长春花碱)inhibitassemblyofmicrotubuleanddestroystructureofspindlebybindingtounpolymerizedtubulindimers

--Taxol(紫杉醇:红豆杉属植物中的一种复杂的次生代谢产物,促进微管聚合和稳定已聚合微管的药物)makethemicrotubulespolymerizedstable.224)Typesofmicrotubules◆Composition:●singlet（单管：13条原纤维)●doublet（双联管）●triplet（三联管）spindleMTA(13)为完全微管B（10条），C(10)23◆stability(稳定性):●unstablemicrotubules(短寿)●stablemicrotubules(长寿)245)FunctionsAsascaffold(支架)

：maintaincellshape

(protuberanceofcell,suchascivil,flagellaandaxone).25

localizationoforganellesERGCnucleus26Asthetracksoftheintracellularsubstancetraffic(鱼的色素细胞)27作为驱动蛋白与动力蛋白运输轨道神经元细胞28FormationofmitoticspindleMTparticipateincellplateformation

inhigherplantcells.spindlepolekinetochoreMTshorteningAnaphase:spindlepolemovingoutward29Ascrucial

componentofbasalbodiesandcentrosome近基体30Movementofflagella(鞭毛)andcilia

(纤毛)鞭杆基体apairofsingle

microtubule“9+2”characteristicarrangementATPbindingsite中央鞘外动力蛋白臂flagella(鞭毛)orcilia：

consistofplasmamembraneandaxoneme(轴丝)31◆纤毛动力蛋白(ciliarydynein)●是多头的动力蛋白●基部同A管相连●头部同相邻的B管相连●头部具有ATP结合位点，能够水解ATP。32◆Movementme